Many methods have been developed to bind reports and other documents. One common method is the use of the flexible comb binding as sold by GBC Co. This binding has a plastic backing from which extends a series of adjacent plastic loops which each have an unattached, free end. The resiliency of the loops causes the free ends to curl in a circle to engage the backing to effectively form a closed loop. The documents to be bound are punched with rectangular holes along the inner edge of the documents to permit a loop to pass through each hole. A machine available from GBC and other sources is employed to open up the loops sufficiently to allow a person to fit the documents onto the loops. The machine then allows the loops to close, effectively binding the report.
The flexible comb binding comes in a variety of sizes, depending on the thickness of the document. However, it is common to use a binding having a larger diameter than the thickness of the document itself, resulting in the comb binding interfering with the normal use, appearance and storage of the document. For example, it is difficult to stack a series of documents bound by such a flexible comb binding as the binding has a greater diameter than the document thickness. Also, the flexible comb binding can catch on edges and interfere with the operation of the report and the plastic loops often pull apart from the document cover and sheets. Unlike conventionally bound books with titles printed on their spines, plastic comb binding makes spine titling very difficult. Without the title printed on the spine of a report, the report can't be identified from its edge.
Other bindings are common as well. Spiral binding is, literally, spiral wire or plastic coils which bind, for example, school writing pads and many reports bound by professional binderies. Spiral bindings, both metal and plastic, use round holes in the documents being bound. Another binding is metal loops or loop wire binding. A twin loop wire binding is common on planners.
All of these methods of binding perform the function of permitting the turning of pages in the bound report. However, the bindings are exposed and are thicker than the report itself, so that the reports can't be stacked flat like books. None of the binding methods provide for convenient spine titling, making filing, finding and retrieval of the report more difficult.